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Measure mean signal level in the converters.

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Rearrange the meaning of the measured power level to be consistent
with the signal level.
This commit is contained in:
Oliver Jowett 2016-11-12 14:07:58 +00:00
parent 8182dc9a8f
commit cc47718a2d
5 changed files with 79 additions and 37 deletions
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99
convert.c
View file

@ -30,11 +30,13 @@ static void convert_uc8_nodc(void *iq_data,
uint16_t *mag_data,
unsigned nsamples,
struct converter_state *state,
double *out_power)
double *out_mean_level,
double *out_mean_power)
{
uint16_t *in = iq_data;
unsigned i;
uint64_t power = 0;
uint64_t sum_level = 0;
uint64_t sum_power = 0;
uint16_t mag;
MODES_NOTUSED(state);
@ -43,45 +45,58 @@ static void convert_uc8_nodc(void *iq_data,
for (i = 0; i < (nsamples>>3); ++i) {
mag = Modes.maglut[*in++];
*mag_data++ = mag;
power += (uint32_t)mag * (uint32_t)mag;
sum_level += mag;
sum_power += (uint32_t)mag * (uint32_t)mag;
mag = Modes.maglut[*in++];
*mag_data++ = mag;
power += (uint32_t)mag * (uint32_t)mag;
sum_level += mag;
sum_power += (uint32_t)mag * (uint32_t)mag;
mag = Modes.maglut[*in++];
*mag_data++ = mag;
power += (uint32_t)mag * (uint32_t)mag;
sum_level += mag;
sum_power += (uint32_t)mag * (uint32_t)mag;
mag = Modes.maglut[*in++];
*mag_data++ = mag;
power += (uint32_t)mag * (uint32_t)mag;
sum_level += mag;
sum_power += (uint32_t)mag * (uint32_t)mag;
mag = Modes.maglut[*in++];
*mag_data++ = mag;
power += (uint32_t)mag * (uint32_t)mag;
sum_level += mag;
sum_power += (uint32_t)mag * (uint32_t)mag;
mag = Modes.maglut[*in++];
*mag_data++ = mag;
power += (uint32_t)mag * (uint32_t)mag;
sum_level += mag;
sum_power += (uint32_t)mag * (uint32_t)mag;
mag = Modes.maglut[*in++];
*mag_data++ = mag;
power += (uint32_t)mag * (uint32_t)mag;
sum_level += mag;
sum_power += (uint32_t)mag * (uint32_t)mag;
mag = Modes.maglut[*in++];
*mag_data++ = mag;
power += (uint32_t)mag * (uint32_t)mag;
sum_level += mag;
sum_power += (uint32_t)mag * (uint32_t)mag;
}
for (i = 0; i < (nsamples&7); ++i) {
mag = Modes.maglut[*in++];
*mag_data++ = mag;
power += (uint32_t)mag * (uint32_t)mag;
sum_level += mag;
sum_power += (uint32_t)mag * (uint32_t)mag;
}
if (out_power) {
*out_power = power / 65535.0 / 65535.0;
if (out_mean_level) {
*out_mean_level = sum_level / 65536.0 / nsamples;
}
if (out_mean_power) {
*out_mean_power = sum_power / 65535.0 / 65535.0 / nsamples;
}
}
@ -89,10 +104,10 @@ static void convert_uc8_generic(void *iq_data,
uint16_t *mag_data,
unsigned nsamples,
struct converter_state *state,
double *out_power)
double *out_mean_level,
double *out_mean_power)
{
uint8_t *in = iq_data;
float power = 0.0;
float z1_I = state->z1_I;
float z1_Q = state->z1_Q;
const float dc_a = state->dc_a;
@ -101,6 +116,7 @@ static void convert_uc8_generic(void *iq_data,
unsigned i;
uint8_t I, Q;
float fI, fQ, magsq;
float sum_level = 0, sum_power = 0;
for (i = 0; i < nsamples; ++i) {
I = *in++;
@ -118,25 +134,32 @@ static void convert_uc8_generic(void *iq_data,
if (magsq > 1)
magsq = 1;
power += magsq;
*mag_data++ = (uint16_t)(sqrtf(magsq) * 65535.0 + 0.5);
float mag = sqrtf(magsq);
sum_power += magsq;
sum_level += mag;
*mag_data++ = (uint16_t)(mag * 65535.0 + 0.5);
}
state->z1_I = z1_I;
state->z1_Q = z1_Q;
if (out_power)
*out_power = power;
if (out_mean_level) {
*out_mean_level = sum_level / nsamples;
}
if (out_mean_power) {
*out_mean_power = sum_power / nsamples;
}
}
static void convert_sc16_generic(void *iq_data,
uint16_t *mag_data,
unsigned nsamples,
struct converter_state *state,
double *out_power)
double *out_mean_level,
double *out_mean_power)
{
uint16_t *in = iq_data;
float power = 0.0;
float z1_I = state->z1_I;
float z1_Q = state->z1_Q;
const float dc_a = state->dc_a;
@ -145,6 +168,7 @@ static void convert_sc16_generic(void *iq_data,
unsigned i;
int16_t I, Q;
float fI, fQ, magsq;
float sum_level = 0, sum_power = 0;
for (i = 0; i < nsamples; ++i) {
I = (int16_t)le16toh(*in++);
@ -162,25 +186,32 @@ static void convert_sc16_generic(void *iq_data,
if (magsq > 1)
magsq = 1;
power += magsq;
*mag_data++ = (uint16_t)(sqrtf(magsq) * 65535.0 + 0.5);
float mag = sqrtf(magsq);
sum_power += magsq;
sum_level += mag;
*mag_data++ = (uint16_t)(mag * 65535.0 + 0.5);
}
state->z1_I = z1_I;
state->z1_Q = z1_Q;
if (out_power)
*out_power = power;
if (out_mean_level) {
*out_mean_level = sum_level / nsamples;
}
if (out_mean_power) {
*out_mean_power = sum_power / nsamples;
}
}
static void convert_sc16q11_generic(void *iq_data,
uint16_t *mag_data,
unsigned nsamples,
struct converter_state *state,
double *out_power)
double *out_mean_level,
double *out_mean_power)
{
uint16_t *in = iq_data;
float power = 0.0;
float z1_I = state->z1_I;
float z1_Q = state->z1_Q;
const float dc_a = state->dc_a;
@ -189,6 +220,7 @@ static void convert_sc16q11_generic(void *iq_data,
unsigned i;
int16_t I, Q;
float fI, fQ, magsq;
float sum_level = 0, sum_power = 0;
for (i = 0; i < nsamples; ++i) {
I = (int16_t)le16toh(*in++);
@ -206,15 +238,22 @@ static void convert_sc16q11_generic(void *iq_data,
if (magsq > 1)
magsq = 1;
power += magsq;
float mag = sqrtf(magsq);
sum_power += magsq;
sum_level += mag;
*mag_data++ = (uint16_t)(sqrtf(magsq) * 65535.0 + 0.5);
}
state->z1_I = z1_I;
state->z1_Q = z1_Q;
if (out_power)
*out_power = power;
if (out_mean_level) {
*out_mean_level = sum_level / nsamples;
}
if (out_mean_power) {
*out_mean_power = sum_power / nsamples;
}
}
static struct {

3
convert.h
View file

@ -27,7 +27,8 @@ typedef void (*iq_convert_fn)(void *iq_data,
uint16_t *mag_data,
unsigned nsamples,
struct converter_state *state,
double *out_power);
double *out_mean_level,
double *out_mean_power);
iq_convert_fn init_converter(input_format_t format,
double sample_rate,

2
demod_2400.c
View file

@ -360,7 +360,7 @@ void demodulate2400(struct mag_buf *mag)
/* update noise power */
{
double sum_signal_power = sum_scaled_signal_power / 65535.0 / 65535.0;
Modes.stats_current.noise_power_sum += (mag->total_power - sum_signal_power);
Modes.stats_current.noise_power_sum += (mag->mean_power * mag->length - sum_signal_power);
Modes.stats_current.noise_power_count += mag->length;
}
}

9
dump1090.c
View file

@ -246,9 +246,10 @@ void modesInit(void) {
static void convert_samples(void *iq,
uint16_t *mag,
unsigned nsamples,
double *power)
double *mean_level,
double *mean_power)
{
Modes.converter_function(iq, mag, nsamples, Modes.converter_state, power);
Modes.converter_function(iq, mag, nsamples, Modes.converter_state, mean_level, mean_power);
}
//
@ -445,7 +446,7 @@ void rtlsdrCallback(unsigned char *buf, uint32_t len, void *ctx) {
// Convert the new data
outbuf->length = slen;
convert_samples(buf, &outbuf->data[Modes.trailing_samples], slen, &outbuf->total_power);
convert_samples(buf, &outbuf->data[Modes.trailing_samples], slen, &outbuf->mean_level, &outbuf->mean_power);
// Push the new data to the demodulation thread
pthread_mutex_lock(&Modes.data_mutex);
@ -538,7 +539,7 @@ void readDataFromFile(void) {
slen = outbuf->length = MODES_MAG_BUF_SAMPLES - toread/bytes_per_sample;
// Convert the new data
convert_samples(readbuf, &outbuf->data[Modes.trailing_samples], slen, &outbuf->total_power);
convert_samples(readbuf, &outbuf->data[Modes.trailing_samples], slen, &outbuf->mean_level, &outbuf->mean_power);
if (Modes.throttle) {
// Wait until we are allowed to release this buffer to the main thread

3
dump1090.h
View file

@ -255,7 +255,8 @@ struct mag_buf {
uint64_t sampleTimestamp; // Clock timestamp of the start of this block, 12MHz clock
struct timespec sysTimestamp; // Estimated system time at start of block
uint32_t dropped; // Number of dropped samples preceding this buffer
double total_power; // Sum of per-sample input power (in the range [0.0,1.0] per sample), or 0 if not measured
double mean_level; // Mean of normalized (0..1) signal level
double mean_power; // Mean of normalized (0..1) power level
};
// Program global state